Using techniques previously developed in my laboratory for the isolation and propagation of murine alloreactive T cell clones, this project has as its specific aims the characterization of T cell receptors for alloantigen, identification and characterization of hybrid histocompatibility determinants in species other than the laboratory mouse and specific induction of organ allograft tolerance. These three specific aims have as their underlying theme recognition and control of alloagression. Thus, if we can understand the nature of T cell receptors for alloantigen, it might be possible to specifically modulate the recognition of certain alloantigens which will be of importance in organ transplantation. Whether or not there exist "hybrid 1a" products on human cells is of utmost importance in understanding potential transplantation phenomena. Thus, our ability to show that such "hybrid 1a" molecules exist on other mammalian species is of interest in understanding their potential importance for alloantigen recognition in human organ transplants. Finally, if we can resolve the two questions raised above, it might be possible to specifically modulate organ allograft tolerance initially in experimental models of murine organ allo-transplantation with ultimate application to human models of organ transplantation across MHC barriers. These techniques all involve methodology which was developed or is currently ongoing in my laboratory.